﻿using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace FP
{
    class ResClass
    {
        // ref 有进有出
        public void Enter(ref string a,string b,string c)
        {
            a = a + b + c;
        }
        //out 只出不进
        public void Come(out string a,string b,string c)
        {
            a = b + c;
        }
    }
}
    


